Field
The present subject matter relates to wireless electric power transmission.
Description of Related Art
Nowadays, a wireless electric power transmission system is known that includes an electric power transmission apparatus which wirelessly (contactlessly) transmits electric power, and an electric power reception apparatus which receives the electric power supplied from the electric power transmission apparatus, without being interconnected through a connector. According to Japanese Laid-Open Patent Application No. 2012-251374, a key that wirelessly locks and unlocks a door of an automobile is provided with a switch for instructing an electric power transmission apparatus to start transmitting electric power.
In a case in which an object (e.g., a foreign object such as a conductor) that does not support wireless electric power transmission is placed within a range in which the electric power transmission apparatus can transmit wireless electric power, there may arise a problem in which the object generates heat. A conceivable countermeasure against such a problem is to find, through communication, whether the object placed within the range in which the electric power transmission apparatus can transmit wireless electric power supports wireless electric power transmission. In a case in which a remaining battery capacity of an electric power reception apparatus is too low to carry out such communication, however, the electric power transmission apparatus cannot establish communication with the electric power reception apparatus and may determine that the electric power reception apparatus is a foreign object, and thus the electric power reception apparatus may not start charging.
It is possible to give instructions for starting wireless electric power transmission based on a user operation according to Japanese Laid-Open Patent Application No. 2012-251374. However, wireless electric power transmission disadvantageously starts even in a case in which the user fails to notice that a foreign object that does not support wireless electric power transmission is present within a range that enables the wireless electric power transmission. Thus, there is room for improvement in such a conventional technique. Namely, in terms of achieving both safety in wireless electric power transmission and convenience in starting wireless electric power transmission even in a case in which the remaining battery capacity of the electric power reception apparatus is low, for example.